Continuous in situ X-ray reflectivity investigation on epitaxial growth of InGaN by metalorganic vapor phase epitaxy

• A continuous in situ X-ray reflectivity (XRR) using a Cu-Kα1 beam was proposed.
• Surface roughening was evaluated as a function of growth time.
• Experimental data for the critical thickness hc of In0.11Ga0.89N/GaN were obtained.
• The experimental hc of InGaN was compared with calculated theoretical hc.
• Continuous in situ XRR investigation of In0.11Ga0.89N SQW was also carried out.

Continuous in situ X-ray reflectivity (XRR) measurements were used to investigate the growth process of an In0.11Ga0.89N epilayer and its single quantum well grown on c-plane GaN/sapphire templates using an in-house-designed metalorganic vapor phase epitaxy installed in a laboratory-grade X-ray diffractometer. The surface roughening of the epilayer as a function of growth time was calculated from the continuous in situ XRR curve. The growth rate, critical thickness hc(r) for surface roughening, and roughening rate were obtained. The experimental critical thickness hc(r) of the In0.11Ga0.89N epilayer analyzed from the continuous in situ XRR curve was 14.8±0.4 nm. Based on the calculated theoretical critical thickness hc and the experimental hc(r,2), Fischer’s model seems to be appropriate for describing the critical thickness of the InGaN/GaN.